Axial piston engines, also called barrel type engines, are crankless, reciprocating internal combustion engines having one or more cylinders, each of which houses two opposed pistons arranged to reciprocate in opposite directions along the longitudinal axis of the cylinder. Crankless engines do not rely on the crankshaft for piston motion, but instead utilize the interaction of forces from the combustion chamber gases, and a rebound device (e.g., a piston in a closed cylinder). A main shaft is disposed parallel to, and spaced from, the longitudinal axis of each cylinder. The main shaft and pistons are interconnected via a swashplate such that reciprocation of the pistons imparts rotary motion to the main shaft. The swashplate has a generally sinusoidal cam surface or track that is engaged by each piston arm to impart axial motion to the piston. The shape of the track can be utilized to control the relative position of the piston head.